e1=sym('a*x^2+b*x+c=0')
classe1=class(e1) 
e2=sym('log(t)^2*t=p')
classe2=class(e2)
e3=sym('sin(x)^2+cos(x)=0')
classe3=class(e3)
e4=sym('Dy-y=x')
classe4=class(e4)
